I'm trying to make visuals for my music, which consists of 4 pictures, 4 adjustment layers (each with 1 evolution keyframe from start to finish on each), & 2 audio spectrums. Being brand new to AE, iss 12 hrs a normal render time upon exporting?

you're under times could be normal or your system could be poorly optimized. Without all of the details of your composition and your render settings it is impossible to know. You're stills could be way too big. You could be rendering to a format that is very slow to render. Or everything could be perfect. Without details it's impossible to say.

After what you said, I went back & noticed that the stills were wayyy too big & after re-editing them, it really did cut the rendering time in half. Now though when rendering, it a) constantly freezes, & b) the estimated render time increases from about 4/5 hrs to 23hrs.

I did read acouple articles lastnight saying what Rick said about Quicktime being buggy & AME being a better option. I'm in the midst of rendering it now w/ AME & so far its at a strady 6hrs but slowwly increasing.

Update: 5minute video going on 45hrs of rendering. This was the only setting that seemed promising because any other setting barely would move after 1hr.

Still something doesn't feel right whether its my computer, settings I'm choosing, or the file from AE itself. I'm pretty lost since it's taken this long for the shortest song/video & i have 9 more to do that are up to 10minutes long.

You can search the forum for hundreds of threads related to improving render times. Precomposing accurately so effects like, say, drop shadows are applied once instead of ten times, pre-rendering reiterative effects, reducing procedural effects like motion blur, properly scaling still images to less RAM-consuming sizes, and, perhaps useful in your case, rendering out to a uncompressed format and then using an encoder to get the h.264 version. I'd say transcoding to h264 on the fly is easily doubling your rendering time. But transcoding to h264 from a finished movie is quite fast.

You're going to need to tell us about your effects and how many layers and what kind of experience you have.

Ah, your lack of experience won't help, I'm afraid. You cannot intuitively decide how to optimize rendering without lots of experience. AE just doesn't work like Photoshop or FCP or Illustrator. You could, hover, transcode your mp3 to aan uncompressed codec and save some processing. You could copy your Audio and Audio Spectrum layers and put them in their own comp and render that out as prores422. Bring the rendered movie back in and replace all those layers with the movie. Adjustment layers are sexy but misleading. You probably are using them incorrectly, most beginners do. Fractal noise can be a rendering slug. Render that as a movie if you can.

Prerendering is basically just looking at your comp and deciding what effects/layers are not dependent on others. Precomposing is a process of grouping layers together to form a desired output that can be fed back into the main comp for a specific effect or filter. The classic example is drop shadow on a rotating object. If you just apply the drop shadow to the rotation object, the shadow is applied before the object is moved and the shadow moves with the object as it rotates, destroying the illusion. If you precompose the rotating object and apply the shadow to the precomp, the movement is rendered before the shadow is applied. It's complicated but you get the hang of it after a few epic rants.